1. Field of the Invention
The present invention pertains to a method for the automatic measurement of convergence and for the automatic determination of corrections to be made in deflectors in order to obtain correct convergence with trichromatic cathode tunes. It also pertains to a machine for the application of the said method.
2. Description of the Prior Art
In general, trichromatic cathode tube deflectors exhibit convergence errors at manufacture, even when the manufacturing is done with great care. At present, to correct these errors, when they are not negligeable, an operator has to adjust each deflector in the right position on a standard trichromatic cathode tube on which a bar test pattern is displayed. Then, depending on the image deformations that he observes on the screen of this tube, the operator proceeds to make mechanical and/or magnetic adjustments of the deflectors by fixing magnetic correction parts on them at the places that he judges to be appropriate. The quality of the finally obtained correction depends on the experience of the operator and on his ability to establish a correct correlation between the phenomena observed on the tube of the screen and the adjustments to be made. Even with a very experienced operator, a correction process of this type is relatively slow: an average of two to four minutes is needed per deflector.